Mixing devices for bone cement are known.
Such a generic mixing device is shown, for example, in the applicant's German patent application DE 10 2007 041 666 A1. When preparing bone cement, a powder, in particular a PMMA powder, is typically mixed with a liquid monomer. Vacuum mixing systems are known so as to avoid the formation of bubbles and/or to prevent harmful gaseous substances that develop during preparation from escaping into the environment. These are systems in which the mixing container comprises a connection for a vacuum hose, via which the container is placed under a vacuum during the mixing process.
Known conventional system often require relatively complicated operation, in which the user must perform several steps associated with sources of errors. In particular, it is important to precisely adhere to the predefined mixing ratio between the monomer and powder.
For this purpose, for example, systems are known in which the monomer is suctioned into the mixing container based on a vacuum that is present in the mixing container. Such conventional systems generally have a valve through which air can flow into the monomer container, so that the existing liquid is completely discharged from the monomer container. Such a system is described, for example, in the European patent specification EP 0 725 647 B1.
The disadvantage of such a system is that the bone cement can become contaminated with microbes from the ambient air, in particular if this system is not operated in a sterile environment.